Invertebrate Zoology: Porifera, Cnidaria, Worm Phyla & Key Terms

Porocyte

Sponge pore; allows water to enter the sponge

Choanocyte

Sponge cell that creates water currents and captures food

Spicules or spongin

Provide skeletal support for sponges

Gemmule

Resistant survival structure that helps a sponge survive harsh conditions

Cnidocyte

Stinging cell found in cnidarians

Nematocyst

Stinging capsule used to capture prey or defend against predators

Colloblast

Sticky cell used to catch prey

Medusa

Jellyfish-like body form that swims freely

Polyp

Attached cnidarian body form

Scyphozoa

Class containing true jellyfish

Cubozoa

Class containing box jellyfish

Anthozoa

Class containing corals and sea anemones

Ecdysozoa

Group of animals that grow by molting their outer covering

Platyhelminthes

Phylum of flatworms

Trematoda

Class of parasitic flatworms called flukes

Scolex

Tapeworm attachment structure that helps it attach to the host

Proglottids

Tapeworm body segments containing reproductive organs

Parthenogenesis

Development of offspring from an unfertilized egg

Nematoda

Phylum of roundworms

Annelida

Phylum of segmented worms

Metamerism

Repetition of body segments

Polychaeta

Group of marine bristle worms

Oligochaeta

Group containing earthworms

Hirudinea

Group containing leeches

Clitellum

Reproductive region that helps form a cocoon in many annelids